ASP2957 for X-linked myotubular myopathy

Inclusion criteria

• {"criterion_text":"- 1. Participant is projected to be ≤ 36 months of age at dosing\n- 2. Participant has molecular genetic report from a CAP-approved testing facility at screening that confirms a diagnosis of XLMTM and harbors a “pathogenic” or “likely pathogenic” variant in the MTM1 gene as classified using the ACMG standards and guidelines for interpretation of sequence variants\n- 3. Participant is ventilator-dependent and meets the following criteria: a. Required respiratory support at birth b.\tRequires ≥ 20 hours per day of invasive ventilator support (confirmed during screening) c.\tHas a tracheostomy tube\n- 4. Participant has no evidence of hepatic peliosis, increased echogenicity or any other clinically important abnormal finding on liver ultrasound as assessed by the investigator in consultation with the site hepatologist\n- 5.\tParticipant’s hepatobiliary laboratory measurements must meet the following criteria during screening and for the 2-month retrospective assessment of participant’s medical history: a. a.\tALT and AST < 3 × ULN b.\tDirect bilirubin ≤ 1 × ULN c.\tSerum total bile acids < 2 × ULN, independent of fasting status\n- 6. Participant’s parent(s) or LAR(s) must provide documentation of being current with recommended immunization schedule according to regional guidelines."}

Exclusion criteria

• {"criterion_text":"- 1. Participant born < 35 weeks gestation is still not term as per corrected age.\n- 10.\tParticipant tests positive for anti-MyoAAV3.8 TAb, as determined by central laboratory testing. a.\tNote: Since very young children may have passive antibodies transferred in utero from the mother, participants ≤ 6 months of age who initially test positive for anti- MyoAAV3.8 TAb may be rescreened for study eligibility.\n- 2. Participant is nutritionally unstable with weight less than fifth percentile for age or has a vitamin A, E or K deficiency.\n- 3. Participant requires supplemental oxygen on a routine or chronic basis. a.\tNote: The use of supplemental oxygen for acute, self-limited illnesses (for example, during hospitalization for pneumonia) shall not be exclusionary, provided the participant is neither acutely ill nor using supplemental oxygen at the time of screening.\n- 4. Participant currently has a clinically important respiratory infection or other clinically important active infection of any kind.\n- 5. Participant has an active viral or bacterial infection including, but not limited to, positive testing for: a.\tTB using the QuantiFERON-TB test b.\tActive HAV, HBV or HCV c.\tPrior HBV or HCV virus infection due to the risk of reactivation associated with immunosuppression d.\tHIV-1 and HIV-2 e.\tCOVID-19 f.\tCMV, viral loads ≥ 500 IU/mL or attributable symptoms or evidence of end-organ disease due to CMV.\n- 6. Participant has any history of cholestatic liver dysfunction and/or treatment for cholestasis. If the participant is taking prophylactic treatment for cholestasis (e.g., ursodiol, cholestyramine, rifampin or other therapies) which has not been prescribed for cholestatic liver dysfunction, treatment must be discontinued for at least 4 weeks prior to signing the ICF. a.\tNeonatal hyperbilirubinemia resolving within 4 weeks of birth in a full-term infant is not an exclusion.\n- 7. Participant has prior history of abnormal transaminases (ALT or AST) and/or abnormal bilirubin metabolism associated with ascites, jaundice (aside from neonatal hyperbilirubinemia) or gastrointestinal bleeding.\n- 8. Other than as required per protocol, participant has received or plans to receive systemic immunomodulating agents within 90 days before day 1 (use of inhaled corticosteroids to manage chronic respiratory conditions is allowed).\n- 9. Participant received any treatment for cholestasis (e.g., ursodiol, cholestyramine, rifampin or other therapies) prior to signing the ICF."}

Primary endpoints

• {"endpoint_text":"- Incidence and severity of TEAEs and AESIs","definition_or_measurement_approach":"As stated: incidence and severity of treatment-emergent adverse events (TEAEs) and adverse events of special interest (AESIs); no further definition provided in the record."}
• {"endpoint_text":"- Change from baseline in the following safety assessments through week 52: o clinical laboratory tests o cardiac findings from ECG and ECHO o muscle findings from muscle MRI and histopathology o physical examinations","definition_or_measurement_approach":"Change from baseline measured through week 52 for listed safety assessments (clinical laboratory tests; ECG and ECHO cardiac findings; muscle MRI and histopathology findings; physical examinations)."}

Secondary endpoints

• {"endpoint_text":"- Change from baseline in hours per day of ventilation support at week 52","definition_or_measurement_approach":"Change from baseline measured at week 52 in daily hours of ventilation support."}
• {"endpoint_text":"- ASP2957 vector DNA in serum through week 52","definition_or_measurement_approach":"Measurement of ASP2957 vector DNA in serum through week 52."}
• {"endpoint_text":"- ASP2957 vector DNA in muscle biopsy at week 52","definition_or_measurement_approach":"Measurement of ASP2957 vector DNA in muscle biopsy at week 52."}
• {"endpoint_text":"- ASP2957 vector DNA in saliva, urine and stool","definition_or_measurement_approach":"Measurement of ASP2957 vector DNA in saliva, urine and stool (timeframe not further specified beyond 'through week 52' for other viral shedding endpoints)."}
• {"endpoint_text":"- Immunogenicity of ASP2957 through week 52 as assessed with the following tests: o Anti-MyoAAV3.8 TAb and NAb o Anti-myotubularin Tab","definition_or_measurement_approach":"Assessment of immunogenicity through week 52 using assays for Anti-MyoAAV3.8 total antibodies (TAb) and neutralizing antibodies (NAb), and Anti-myotubularin antibodies."}

Methods

• Parent/guardian recruitment materials (document: K2_Recruitment Material_Parent Letter) — target audience: parents/caregivers of eligible participants
• HCP referral materials (document: K2_Recruitment Material_HCP Referral Letter) — target audience: healthcare professionals for referral
• Study discussion guide for recruiters (document: K2_Recruitment Material_Study Discussion Guide)
• Study introduction multifold (document: K2_Recruitment Material_Study Introduction Multifold)
• Recruitment arrangements document (K1_Recruitment arrangements) — administrative recruitment plan (content not extracted in text fallback)
• Recruitment appears site-based at the listed France paediatric hospital site (Assistance Publique Hopitaux De Paris)

France

Earliest CTIS Part Ii Submission Date

03-12-2025

Latest Decision Or Authorization Date

06-05-2026

Processing Time Days

154

Number Of Sites

1

Number Of Participants

3

Primary sponsor

Full Name

Astellas Gene Therapies Inc.

Organisation Type

Pharmaceutical company

Country Of Registered Address

United States

Contract research organisations

Name

PPD International Holdings LLC

Responsibilities

Laboratory Analysis

Name

Icon Clinical Research Limited

Responsibilities

Translation

Name

IQVIA Limited

Responsibilities

IVRS - Treatment Randomisation

Name

Fortrea Inc.

Name

Pharmaceutical Product Development LLC

Responsibilities

Laboratory Analysis

Name

WCG Clinical Inc.

Responsibilities

IDMC coordination

Third parties

• {"country":"United States","full_name":"WCG Clinical Inc.","duties_or_roles":"IDMC coordination","organisation_type":"Pharmaceutical company"}
• {"country":"Belgium","full_name":"PPD International Holdings LLC","duties_or_roles":"Laboratory Analysis","organisation_type":"Pharmaceutical company"}
• {"country":"Ireland","full_name":"Icon Clinical Research Limited","duties_or_roles":"Translation","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Bioagilytix Labs LLC","duties_or_roles":"Laboratory Analysis","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Modus Outcomes LLC","duties_or_roles":"Patient interviews","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Fortrea Inc.","duties_or_roles":"","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Pharmaceutical Product Development LLC","duties_or_roles":"Laboratory Analysis","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Medidata Solutions Inc.","duties_or_roles":"","organisation_type":"Non-Pharmaceutical company"}
• {"country":"United States","full_name":"Red Nucleus Solutions LLC","duties_or_roles":"Ventilator Data Collection","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Trinds LLC","duties_or_roles":"Physical Therapy Training and QC","organisation_type":"Pharmaceutical company"}
• {"country":"United States","full_name":"Diverge Translational Science Laboratory","duties_or_roles":"Laboratory Analysis","organisation_type":"Laboratory/Research/Testing facility"}
• {"country":"United States","full_name":"Fulgent Genetics Inc.","duties_or_roles":"Laboratory Analysis","organisation_type":"Laboratory/Research/Testing facility"}
• {"country":"United Kingdom","full_name":"Mde Services Group Limited","duties_or_roles":"Home health, in-home HCP assessments","organisation_type":"Non-Pharmaceutical company"}
• {"country":"United Kingdom","full_name":"IQVIA Limited","duties_or_roles":"IVRS - Treatment Randomisation","organisation_type":"Pharmaceutical company"}